The present invention relates to pulsation dampeners used on oil free screw compressors to suppress the pressure pulsations generated by the compressor airend. A pulsation dampener reduces the mechanical vibrations in the downstream piping system caused by the pressure pulsations originating from the outlet of the compressor. If these pulsations are left undamped, the pulsations can damage the piping system, coolers, moisture separator, valves and ancillary equipment. Pulsation dampeners reduce noise heard from the compressor by reducing the pressure pulsations inside the piping system.
The venturis 10 and 15 shown in FIGS. 1-2 and 3-4, respectively, are currently used to reduce pressure pulsations. A venturi is a high pass acoustical device. A high pass device attenuates pressure pulsations having low frequencies while allowing high frequency pressure pulsations to pass through the device. Oil free compressor applications require a low pass acoustical device. A low pass acoustical device attenuates the high frequencies and allows low frequencies to pass through the device. The venturi does offer some attenuation at the higher frequencies, but the attenuation is not sufficient (i.e., does not cover broad ranges of frequencies) to reduce all of the pulsations. Insufficient attenuating of the high frequency pressure pulsations by the venturi have resulted in high noise levels, damage to check valves, cooler failures and ringing piping systems.